1. Field of the Invention
The invention relates to a receiver for receiving reception signals of a first type, for example, TV signals, and reception signals of a second type, for example, FM-radio signals. The invention also relates to a multimedia apparatus incorporating such a receiver. The receiver may enhance the functionality of the multimedia apparatus with, for example, TV and FM-radio reception. The multimedia apparatus may be in the form of a personal computer (PC) having slots into which add-on cards are plugged. The receiver may be implemented on one of these add-on cards. Accordingly, the PC can access information transmitted by FM-radio and TV stations.
2. Description of the Related Art
A receiver capable of receiving TV and FM-radio signals is described in U.S. Pat. No. 5,148,280. The prior-art receiver comprises a single tuner for both TV and FM-radio reception. The single tuner frequency converts both a selected FM-radio signal and a selected TV signal to a fixed intermediate frequency (IF) signal of approximately 40 MHz. An IF of approximately 40 MHz is common for TV reception.
The IF signal produced by the tuner is processed differently for TV or FM-radio reception. For TV reception, the IF signal is processed in a manner which is very similar to IF signal processing in most present-day TV receivers. The IF signal is applied to a TV IF demodulation unit via a surface acoustic wave (SAW) filter. The TV IF demodulation unit provides a baseband composite video signal and a TV sound carrier signal. The TV sound carrier signal is further processed in a TV sound channel which provides, in response, baseband audio signals.
For FM reception, the IF signal is supplied to a single chip FM-radio integrated circuit (IC) via a filter unit which includes a 43.3 MHz band-pass filter and a 48.65 MHz trap. In the FM-radio IC, the IF signal is frequency-converted to obtain a nominal 10.7 MHz FM IF signal. The FM IF signal is filtered by a ceramic filter arrangement and amplified, detected and decoded in the FM-radio IC. Thus, for FM reception, the prior-art receiver employs a double conversion scheme. The tuner performs a first frequency conversion and the FM-radio IC performs a second frequency conversion.
The filter unit, which is coupled between the tuner and the FM-radio IC, has to satisfy relatively strict requirements in order to avoid excessive distortion of the FM-radio signal to be received. First, the passband of the filter unit needs to be sufficiently close to 43.3 MHz. This requirement follows, among other things, from the frequency characteristic of the tuner, which is haystack-like, and the characteristics of the signals to be received. Secondly, the 46.85 MHz trap included in the filter unit needs to be accurately tuned to that frequency so as to avoid an image reception problem in the second frequency conversion.
Although the receiver described in U.S. Pat. No. 5,148,280 uses a single tuner for both TV and FM-radio reception, implementations of the prior-art receiver will be relatively spacious. The filter unit, which is coupled between the tuner and the FM-radio IC, is built up with discrete capacitors and inductors. In order that the filter unit satisfies the above described requirements, the inductors need to have a certain size. If not, the inductors will have a too low quality factor to achieve an adequate selectivity and accuracy.